Pediatric AIDS is a growing concern, particularly int he inner city areas served by our team. Recent surveys have demonstrated that 2-3% rise of pregnant women have evidence of HIV infection and 1000 to 2000 HIV-infected infants may be born per year in New York. This application proposes to utilize the resources of our Adult and Pediatric AIDS Clinical Trials Unit (ACTU) to conduct studies related to early diagnosis of pediatric HIV infection. They have developed a consortium of hospitals and investigators with the capability to develop protocols, to recruit patients with HIV infection, coordinate data and specimen collection, perform virologic and immunologic evaluations, maintain quality control of laboratory results and data entry, and collaborate with other institutions involved in trials. They will identify a cohort of HIV-positive pregnant women and HIV-negative controls and perform sequential prenatal and postnatal testing for HIV with a variety of techniques including ELISA and Western Blot for anti-HIV antibody, P24 viral antigen, viral culture and polymerase chain reaction to determine which test or combination of tests gives the earliest and most accurate prediction of true HIV infection. The studies will be conducted at hospitals serving two of the highest AIDS incidence areas in the country - East Harlem and Manhattan's lower East Side, as well as Elmhurst, Queens, an area with a high proportion of immigrants from areas of the world where AIDS is transmitted heterosexually. The combined obstetrics service at the participating hospitals perform over 8,000 deliveries per year and estimate 75 to 150 HIV-infected mothers. Large well designed studies are essential if they are to improve our ability to treat children with HIV infection.